Modular dry-air evaporative cooler

ABSTRACT

Air conditioning apparatus for the sensible cooling of useable air by the evaporative process at a cost of operation substantially lower than that of mechanical refrigeration of the same capabilities, and advantageously comprised of modular evaporator and blower units and multiple stages thereof with the use of substantially permanent inexpensive plastic materials conducive to the efficient absorption of heat between separate columns of air, one column subject to the evaporative cooling process with no energy change, and the other column subject to the sensible cooling process with a subtraction of energy from the useable air.

BACKGROUND

.Iadd.This application is a continuation of Ser. No. 183,107 filed Sept.2, 1980, now abandoned, which is for Reissue of U.S. Pat. No. 3,877,244granted Apr. 15, 1975 based on Ser. No. 368,756 filed June 11,1973..Iaddend.

Reference is made to my U.S. Pat. No. 3,214,936 entitled DRY-AIREVAPORATIVE COOLER issued Nov. 2, 1965 wherein there is a separation ofair into two columns, one column subject to evaporation and the other anisolated column of useful air subject to sensible cooling. The unitconstruction and materials employed in the fabrication of said patentedcooler has limited use and is not the least costly. As to use, saidpatented cooler and others of the prior art are each of a determinedcapacity and require specified design for specific installations. And asto materials of construction, they have been fabricated of metals,reference being made to the heat transfer tubes which are presumablymetallic for efficient heat transfer. However, as will be hereinafterdisclosed, the presumptive use of metals of high thermal conductivity isnot necessarily required in heat transfer means of the type underconsideration; and on the contrary it has been discovered that efficientevaporative modules with sensible air passages are advantageouslyfabricated of plastic materials which have lower thermal conductivity ascompared, for instance, with aluminum or copper. Therefore and inaccordance with this invention, I provide modular components for theconstruction of air cooler installations to specification ascircumstances require, and of durable inexpensive materials. With thepresent invention, there is economy in both installation and operation,while satisfying the temperature drop requirements as desired.

The construction and installation of prior art evaporate coolers hasbeen made according to specification requirements, with the coolingcapacity or cubic foot per minute capacity in mind. Also, with ordinarysimple evaporative units (not compound) the temperature drop is notentirely predictable and not altogether controllable. On the contrary, awide range of predicted controllability is aforded with mechanicalrefrigeration, but at great expense both in high installation costs andhigh operation costs. In fact, there is such a vast difference in thenormal capabilities of evaporative cooling as compared with mechanicalrefrigeration cooling, that evaporative cooling is seldom if everconsidered for use where precisely controlled high temperature drop withabsolute humidity is a requirement. However, with the present invention,predictably high temperature drop is controlled in a dry-air evaporativecooler, utilizing separated columns of evaporative cooled air andsensible cooled air passing separately through modular cores withcooling compounded by utilizing multiple stages. As will be described, aportion of the sensibly cooled air from one state is directed throughthe evaporative chamber of another stage that sensibly cools theremaining portion of air from said one stage, with an efficient andpredictable temperature drop in each instance. The number of stagesemployed is determinative of the total temperature drop, ascircumstances require.

The economical fabrication of heat exchanger cores has been a problem inthe design of condensers and the like, and where high pressures areemployed the tubes extending through fluid handling chambers must bepressure sealed at opposite headers. However, evaporative coolers (notso with mechanical refrigerators) deal with lower pressures wherein itis feasible to employ the press fitting together of plastic and/orelastomeric parts and elements. It is to this end, therefore, that it isan object of this invention to employ a core structure fabricated ofinexpensive plastic materials that are conducive to cleanliness andwhich are not adversely restrictive to the efficient heat transfer.

It is also an object of this invention to provide compatible evaporatorand blower modules that are adapted to be cooperatively combined for themovement of separated columns of evaporative and sensible cooled air.Firstly, it is an evaporative module that is provided with a heattransfer core through which the two columns of air pass in directionsrelative or normal to each other. Secondly, it is a blower module thatis provided with air pump means which transports the air on a singleaxis therefrom. A characteristic feature of the modules is their cubicconfigurations, preferably square, and the total use of space within theconfines of the side walls thereof.

It is still another object of this invention to provide the efficientheat transfer between two columns of air and especially between a columnof evaporatively cooled air and a column of sensibly cooled air. It isthe unobvious effect of efficient heat absorption from the evaporativeprocess when employing tubes of low heat transfer capability throughwhich sensibly cooled air is passed. Since the most restrictive heattransfer rate is that into the sensibly cooled air within the tube, theless restrictive heat transfer rates through the tube core and betweenthe wetted exterior of the tubes and evaporative air are unobviouslynon-restrictive. Therefore, it is in fact feasible to employ inexpensiveplastic tubes of relatively low thermal conductivity as the heatexchange tubes of the cores as they are hereinafter described.

DRAWINGS

The various objects and features of this invention will be fullyunderstood from the following detailed description of the typicalpreferred form and application thereof, throughout which descriptionreference is made to the accompanying drawings, in which:

FIG. 1 is a perspective view of a typical arrangement of componentscomprising the cooperative combination of evaporator and blower modulesjoined by a diffuser.

FIG. 2 is a perspective view of one of the evaporative modules shown inFIG. 1.

FIG. 3 is a perspective view of one of the blower modules shown in FIG.1.

FIG. 4 is an exploded diagram of the modules arranged as shown in FIG. 1and separated in order to illustrate their individuality.

FIG. 5 is an elevational sectional view of the evaporator module takenas indicated by line 5--5 on FIG. 2.

FIG. 6 is a perspective view of one of the tubes which characterizes theinvention.

FIG. 7 is an enlarged fragmentary sectional view taken as indicated byline 7--7 on FIG. 6.

FIG. 8 is an elevational sectional view of the blower module taken asindicated by line 8--8 on FIG. 3, and

FIG. 9 is a perspective view similar to FIG. 1 and illustrates a secondembodiment of the invention.

PREFERRED EMBODIMENT

The phenomenon of "evaporative" cooling is a well known effect, in whichprocess decrease in energy as a result of air temperature decrease isregained in the form of moisture; the net result being no change inenergy. However, in a "sensible" cooling process there is a change inenergy (Enthalphy) by not admitting moisture; the net result being asubtraction of energy from the air. The obvious disadvantage of ordinaryevaporative cooling is the addition of moisture to the useful air,whereas the advantage of sensible cooling is that there is no change inabsolute humidity during the cooling process of useful air. Reference ismade to mechanical refrigeration means normally employed in sensiblecooling processes, and all of which is to be compared with the dry-airevaporative cooler which is the subject of said U.S. Pat. No. 3,214,936where there is a separation of air into refrigerated air subject toevaporation of water and useful air in which there is no humiditychange, and wherein conventional construction and materials areemployed.

In accordance with the present invention it is the dry-air evaporativeprinciple that is employed, but with improvements relating to efficiencycoupled with economy, and to universal applicability with controlledoutput of useful air. Efficiency and economy is realized by fabricationof inexpensive but effective materials, and controlled applicability isrealized by the cooperation of modules combined as may be required. Itis the volume of air to be processed which varies in requirement witheach installation and which is adapted to by the concept hereindisclosed.

Reference is made to Disclosure Document No. 014607, filed Nov. 6, 1972,and to FIGS. 6 and 7 of the drawings herein, wherein heat transfer tube10 of plastic material are advantageously employed. It is the unobviousutility of material having low thermal conductivity as related to thatof the evaporative medium such as water, which nevertheless producesthis efficient and practical sensible cooling system employing theevaporative cooling principle in the primary cooling process.

The heat transfer tube 10 is a plastic evaporative cooler elementcomprising a heat conductive wall 11, a material such aspolyvinylchloride known as PVC, with one side thereof in contact withthe evaporative medium, such as water, and with the other side thereofin contact with the fluid to be cooled, such as the sensible cooleduseful air. It is the characteristic of this invention that two columnsof fluid are separated by the heat conductive wall 11 having one side toreceive the evaporative medium and give up heat and the other side toreceive or take up heat. The heat conductive wall can be a plate or thelike, in lieu of a tube, and the evaporative outside is surfaced as forexample with gauze 12 as best illustrated in FIG. 7 of the drawings. Thesaid other inside has interfacial contact with the air from which heatis sensibly absorbed. It has been discovered that the use of highlyconductive and expensive materials in the fabrication of the heattransfer wall 11 is quite unnecessary. In other words, the use of metalssuch as copper and aluminum in no way enhances the operation of the heatexchanger wall made thereof when employed in an evaporative cooler ofthe type under consideration where the heat conductivity differential atthe water to material interface is roughly a ratio of 450 to 1. Considertherefore, the following:

    ______________________________________                                        THERMAL CONDUCTIVITY OF ELEMENTS                                              ______________________________________                                        Aluminum        135.000 BTU/HR/Sq Ft/*F/Ft                                    Water           .330    "                                                     Air             .160    "                                                     Water Vapor     .137    "                                                     Polyvinylchloride (PVC)                                                                       .100    "                                                     ______________________________________                                         *                                                                        

Operation of a conventional cooler with all aluminum tubing wrapped withgauze moistened with water; will produce a 10° to 15° F. temperaturedrop in a 86° day, with a temperature drop of useful air of 0.4 to 0.5of the difference between the inlet and outlet dry-bulb temperatures.Operation of the same cooler with plastic tube made according to thisinvention of 3/4 inch 1/16 inch wall polyvinylchloride (PVC) irrigationpipe also wrapped with gauze and moistened with water produced the same10° to 15° temperature drop and same 0.4 to 0.5 difference between theinlet and outlet dry-bulb temperatures.

Aluminum tubing is costly, while polyvinylchloride (PVC) plastic tube ispresently four times less expensive. The comparison with copper tubingis far more favorable. Consequently, the use of pipe or tubing made ofpolyvinylchloride (PVC) plastic, now readily available, presents newdimensions to the cost structure and potential marketability orusefulness for this plastic fabrication concept.

By way of analogy the following explains the phenomenon employed toadvantage herein: Consider the heat flow rate from air inside of a tube,through the tube and then through a film of water and to the evaporativewater-air interface. This is roughly analogous to a series of flowcontrolling valves; for example, wherein the first valve is a quarterinch valve, the second is a ten inch valve and the third is a one inchvalve. The flow through the quarter inch valve is at a maximum while theflow through the other two valves hardly contributes to the resistance.With this analogy in mind, substitute valves of thermal conductivity forthe flow resistance of each valve given as an example above and it canbe readily concluded that the choke in the heat transfer rate is fromthe air inside of the tube, and this is the controlling factor.Therefore, a superior heat conductivity of the tube is ridiculous andunnecessary.

Referring now to the modules as they are illustrated individually inFIGS. 2 and 3 of the drawings, there is a dry-air evaporative module Xand a blower module Y, the two of which are employed as shown in FIGS. 1and 9; in FIG. 1 as components of a multi-stage cooler, and in FIG. 9 ascomponents of a pre-cooler for a mechanical refrigeration unit R. Themodules X and Y are adapted to be joined one to the other for flow ofair therethrough, and they are adapted to be coupled together by aplenum unit Z. The modules X and Y are three dimensional squares, andthe plenum unit Z is dimensioned accordingly to receive and transportair between the modules coextensively of the cross sections thereof andfrom the open sides and/or open ends. Thus, the modules X and Y areadapted to be placed and/or stacked side by side, end to end, and top tobottom, dependent upon the augmentation required in order to achieve theair delivery capacity desired.

The evaporator module X involves a dry-air evaporative cooler C thatfully occupies the volumetric space between top and bottom panels 15 and16, and in practice there are corner legs 17 that join the panelstogether in spaced parallel planes for receiving and capturing the coreC in working position therebetween. As best illustrated in FIG. 5, thedry-air evaporative cooler core C involves a multiplicity of the tubes10 hereinabove described that extend between headers 18 in which theyare supportably sealed. The headers 18 are identical panels perforatedwith openings 19 into which the opposite end portion 20 of the tubes 10are pressed. The headers 18 are square panels of deformible materialhaving top, bottom and opposite side edges compressed within theconfines of the panels 15 and 16 and opposite side legs 17 when the coreis positioned. Accordingly, the core headers are made of a resilientlycompressible plastic or elastomeric material through which the tubes 10frictionally project with the compression fit assured by the compressedconfinement within the panels and legs. In practice, the on-centerspacing of tubes 10, vertically as well as horizontally, isapproximately two diameters; in which case there is substantial diagonalclearance between tubes for the exterior evaporative process when madedamp by the application of water thereover. Characteristicallytherefore, the dry-air evaporator module X comprises closed top andbottom panels, and open sides and open ends through which separatecolumns of air are free to be transported. The primary cooling processinvolves evaporative cooling over the exterior of the tubes 10 by airflowing transversely over said tubes; and the secondary cooling processinvolves sensible cooling within the interior of the tubes 10 by airflowing longitudinally through said tubes.

Liquid distributing means B is provided to either wet the air or to wetthe tubes and which can vary as circumstances require. As shown, themeans B involves a liquid carrying conduit 21 disposed above eachvertical arrangement of tubes 10. The conduits 21 are joined by amanifold 22 and they are perforated so as to discharge downwardly ontothe vertical arrangements of tubes. As shown, there is a motor drivenpump 23 that recirculates water from a pan or sump 24 formed of thebottom panel 16, and there is a water level controlled water supplymeans L to maintain water at the desired level in said pan. With thisarrangement the exterior of the evaporative tubes 10 are kept constantlywetted.

The blower module Y involves an air pump means P of any suitable typeand preferably a centrifugal fan comprising a blower scroll 25 withopposite end openings 26 between which a barrel type blower wheel 27 isdisposed on a transverse horizontal shaft 28 about which the rotor of adrive motor 29 driveably revolves said wheel. It is to be understoodthat various blower and drive arrangements can be employed, includingaxial flow of fans; any of which will transport air longitudinallythrough the blower module Y which forms an elongate tunnel having topand bottom panels 31 and 32 and opposite side panels 33 also. Inpractice, when employing a centrifugal blower having a scroll 25, theintake end 34 of the module is entirely open into the interior chamberthereof, while the discharge opening 35 of the scroll is substantiallysmaller in cross section than the outlet end 36 of the module; in whichcase a divergent passage member 37 couples said discharge opening withsaid outlet end. Thus, the air delivered by the blower module Y is blownfrom the entire cross sectional area thereof defined by the panels 31,32 and 33.

The evaporator module X is by itself ineffective to deliver useful airand requires air transport means for relative transverse andlongitudinal air flow therethrough. The advantage of the modularconstruction is for adaption to specifications relating to refrigerationor cooling capacity, all of which is readily complied with by employingmultiple combinations of modules X and Y, or a substitute are transportmeans for module Y as shown as a complete mechanical refrigeration unitR is FIG. 9. In any case, separate columns of evaporative cooled air andsensibly cooled useable air are transported under low pressures throughthe modules X at right angles to each other; primary air transverselytherethrough for evaporative cooling over the exterior of tubes 10, andsecondary air longitudinally therethrough for sensible cooling withinthe interior of said tubes. In each instance the blower modules Y are tobe used in transporting the air as clearly shown in FIG. 1.

Referring now to the plenum unit Z, separation of sensibly cooled airfrom the delivery end of an evaporator module X into two columns of airis provided for. This plenum unit can vary widely in design andconfiguration and requires in its broadest sense an inlet 40 and a pairof outlets 41 and 42. The plenum structure is shown as involving top andbottom panels 43 and 44 coplanar with the top and bottom panels ofmodules X and Y to establish imperforate continuations thereof, andimperforate side panels 45 that extend continuously between the sidepanels of said modules. In practice, the plenum is extended laterallybeyond and coextensively over the intake side of the module X into whichit delivers said proportion of sensibly cooled air. The function ofinlet 40 is to receive the total sensibly cooled air delivered by anevaporator module X; the function of outlet 41 is to deliver adetermined portion of said total sensibly cooled air into a second stageevaporator module X for subsequent sensible cooling; and the function ofoutlet 42 is to deliver a determined portion of said total sensiblycooled air into said second stage evaporator module X for subsequentevaporative cooling. The divisible portions of air delivered to outlets41 and 42 can vary as circumstances require dependent upon volume andtemperature drop requirements in each instance. For example, a plenumunit Z providing for substantial equal distribution is shown in FIG. 1wherein the cross sectional area of outlet 42 represented by the dottedlines is 50 percent of the full cross sectional area of outlet 41represented by dotted lines. Consequently, 50 percent of the total flowof sensibly cooled air represented by arrow a is diverted and dischargedas evaporatively cooled air as represented by the arrow b. The primaryair that is evaporatively cooled moves transversely through the modulesX in each instance, and as represented by the arrow c is the first stageof cooling.

Referring now to compound cooler combinations shown as a typicalembodiment in FIG. 1 of the drawings, there is a separate blower moduleY provided for each individual cooling process represented by the arrowsa, b and c. As shown, the blower modules Y are suction blowers whichdraw the proportionate columns of air as described, the sensibly cooleduseful air being delivered from a blower module Y along arrow a, thedivisible evaporative air being delivered from a blower module Y alongarrow b, and the solely evaporative air being delivered from a blowermodule Y along arrow c. The evaporatively cooled air is discharged toatmosphere in each instance. It will be seen that the staging orcompounding of evaporative refrigeration utilizing sensibly cooled aircan be repeated in order to achieve the temperature drop required in thesensibly cooled useful air delivered along the arrow a.

Referring now to FIG. 9 of the drawings, the mechanical refrigerationunit R is represented as a complete and operable commercially availableunit, commonly designated as an "air conditioner." Such a unit R isnormally electrically powered and involves a compressor, an expansionmeans and evaporator for heat absorption, and a condensor means forliquifying the refrigerant for recycling into the compressor etc. Unit Rprovides for the air transport required in the movement of sensiblycooled air through the tubes 10 of evaporator module X, which thencooperatively combines with the unit R as a pre-cooler. Again however,the blower module Y is employed to transport transverse evaporativelycooled air over the tubes 10. This combination provides for the economicfeasibility of pre-cooling air conditioning condensors, so that thecondensor preforms as though it were exposed to a lower ambienttemperature day. For example, a 100° day would be reduced to an 85° day,and this allows the condensor to reject 30 percent to 50 percent moreheat. Collectively, this innovation is proposed for incorporationthroughout metropolitian areas, in which case the power stations wouldnot see the effects of heat storm peak air conditioning demands, thusproviding energy conservation calculated to reduce the temperature ofmake up air at the rate of about 1/10th the horse power presentlyrequired by mechanical refrigeration. This saving in electrical powerwould obviate the "brown and black out" problems. The electrical energycapacity previously held in reserve for heat storm periods can then beused productively for other purposes, new growth requirements, etc.

It will be apparent from the foregoing that a most practical and yetless expensive cooling is provided in which the evaporative medium isseparated from the fluid being cooled, and that this process andapparatus made in accordance therewith is useful for purposes other thanthe cooling of air. Further, energy costs for lowering air temperaturemakes feasible the precooling of air conditioning condensors and thelike, and to the end that there is a substantial conservation of energy.The panels of the evaporative module X are imperforate for the singleheight combinations shown, it being understood that multi-unit heightcombinations of modules X are made with open frame-like panel members 15and/or 16; in this way establishing a single air column c-b subject to ablower means. Unobviously, there is an energy change in the primaryevaporatively cooled air c-b, due to the absorption of heat from thesensible cooled air; and it is this semi-cooled air which is dischargedseparately and isolated from the sensibly cooled useful air.

Having described only typical preferred forms and applications of myinvention, I do not wish to be limited or restricted to the specificdetails herein set forth, but wish to reserve to myself anymodifications or variations that may appear to those skilled in the art:.[.I claim:.].

.Iadd.What is claimed is:.Iaddend.
 1. A .Iadd.rectangular.Iaddend.dry-air evaporative cooler .[.including.]. .Iadd.moduleconsisting essentially of: .Iaddend.a pair .Iadd.only .Iaddend.of.[.spaced.]. .Iadd.imperforate planar .Iaddend.side members .[.and a.]..Iadd.spaced by ep core means .Iadd.with a pair of opposite open sidesthereof extending coextensively between said side members for angularlyrelated movement of two separate columns of air, and with opposed endheaders mounted to said side members perpendicular thereto, the coremeans .Iaddend.having opposite interfaces separating the spaces betweensaid .Iadd.side ep members into two angularly related air passages withwetting means at one interface engaging a primary evaporative column ofair and with the other interface engaging a secondary sensible cooledcolumn of air with heat transfer between said opposite interfaces,.[.the remaining two pairs of opposite sides between said members beingopen therebetween for said angularly related movement of said separatecolumns of air, and both said separate columns of air being movablethrough said two angularly related passages coextensively between thespaced side members.]. .Iadd.wherein the core means is comprised of amultiplicity of spaced parallel rigid and self-supporting tubes ofplastic material mounted at their respective ends in said end headersand defining one of said angularly related air passages through thetubes and through the opposite end headers, said end headers extendingcoextensively between and spacing the side members at one pair ofopposite sides of the core means, said end headers and side membersdefining the other one of said angularly related air passages over thetubes, said cooler module comprising means including said spaced,parallel, and self-supporting tubes of plastic material for obtainingsubstantially the same temperature decrease as a dry-air evaporativecooler module that is other wise the same in size, shape and operationas said rectangular dry-air evaporative cooler module and includingmetal tubes having substantially the same length, rigidity, spacingbetween them, air flow through them, air flow over them, and water flowover them, as said rectangular dry-air evaporative coolermodule..Iaddend.
 2. The dry-air evaporative cooler as set forth in claim1 wherein the pair of spaced side members are of square configurationand spaced dimensionally equal to said squareness. .[.3. The dry-airevaporative cooler as set forth in claim 1 wherein the core means iscomprised of a multiplicity of spaced parallel tubes extending betweenopposite end headers coextensively between said pair of spaced sidemembers..].
 4. The dry-air evaporative cooler as set forth in claim 1.[.wherein the core means is comprised of a multiplicity of spacedparallel tubes extending between opposite end headers coextensivelybetween said spaced members and.].wherein the wetting means is at.[.the.]. .Iadd.an .Iaddend.exterior interface of said tubes.
 5. Thedry-air evaporative cooler as set forth in claim 1 wherein the coremeans is comprised of spaced opposite end headers of resiliently.[.deformible.]. .Iadd.deformable .Iaddend.material extendingcoextensively between said spaced members in and between which spacedparallel tubes are supported in friction fit openings.
 6. The dry-airevaporative cooler as set forth in claim 1 wherein the core means iscomprised of spaced opposite end headers of .Iadd.resiliently deformable.Iaddend.elastomeric material extending coextensively between saidspaced members in and between which spaced parallel tubes are supportedin friction fit openings. .[.7. The dry-air evaporative cooler as setforth in claim 1 wherein the core means is comprised of a multiplicityof spaced parallel tubes of plastic material extending between oppositeend headers coextensively between said spaced members..]. .[.8. Thedry-air evaporative cooler as set forth in claim 1, wherein the coremeans is comprised of a multiplicity of spaced parallel tubes of plasticmaterial extending between opposite end headers coextensively betweensaid spaced members, and wherein the wetting means is gauze wrapping atthe exterior interfaces of said tubes..].
 9. The dry-air evaporativecooler as set forth in claim 1, wherein the core means is comprised ofopposite end headers of .Iadd.resiliently deformable.Iaddend.elastomeric material extending coextensively between saidspaced members in and between which spaced parallel tubes of plasticmaterial are supported in friction fit openings, and wherein the wettingmeans is gauze wrapping at the exterior interfaces of said plastictubes.
 10. A dry-air evaporative cooler including: .[.an.]..Iadd.dry-air .Iaddend.evaporator module comprised of .Iadd.two.Iaddend.spaced members and a core means having opposite interfacesseparating the space between said members into two angularly related airpassages with wetting means at one interface engaging a primaryevaporative column of air and with the other interface engaging asecondary sensible cooled column of air with heat transfer between saidopposite interfaces, .Iadd.said core means comprising a multiplicity ofspaced, parallel, rigid and self-supporting tubes of plastic materialmounted at their ends in end headers mounted to said spaced membersperpendicular thereto, said end headers defining one of said angularlyrelated air passages through the tubes and through the opposite endheaders, said cooler module comprising means including said spaced,parallel, rigid and self-supporting tubes of plastic material forproducing substantially the same temperature decrease as a cooler modulethat is substantially the same in size, shape and operation as saiddry-air evaporator modules, but including metal tubes havingsubstantially the same length, rigidity, dimensions, spacing betweenthem, air flow through them and over them, and water flow over them, assaid dry-air evaporator module, .Iaddend.both said separate columns ofair being .[.moveable.]. .Iadd.movable .Iaddend.through said twoangularly related passages coextensively between the said spacedmembers, and a pair of like blower modules and each comprising meansdrawing air through one of said angularly related air passagescoextensively between said members.
 11. The dry-air evaporative coolercombined of modules as set forth in claim 10, wherein the members are ofrectangular configuration, and wherein the remaining two pairs ofopposite sides between said members are open therebetween for saidangularly related movement of said separate columns of air through saidpair of like blower modules respectively.
 12. The dry-air evaporativecooler combined of modules as set forth in claim 10, wherein the membersare of square configuration and spaced dimensionally equal to saidsquareness, and wherein the remaining two pairs of opposite sidesbetween said members are open therebetween for said angularly relatedmovement of said separate columns of air through said pair of likeblower modules respectively. .[.13. The dry-air evaporative coolercombined of modules as set forth in claim 10, wherein the core means iscomprised of a multiplicty of spaced parallel tubes extending betweenopposite end headers coextensively between said spaced members, whereinthe members are of rectangular configuration, and wherein the remainingtwo pairs of opposite sides between said members are open therebetweenfor said angularly related movement of said separate columns of airthrough said pair of like blower modules respectively..].
 14. Thedry-air evaporative cooler combined of modules as set forth in claim 10,wherein the core means is comprised of a multiplicity of spaced paralleltubes extending between opposite end headers coextensively between saidspaced members, wherein the members are of squared configuration andspaced dimensionally equal to said squareness, and wherein the remainingtwo pairs of opposite sides between said members are open therebetweenfor said angularly related movement of said separate columns of airthrough said pair of like blower modules respectively.
 15. A compounddry-air evaporative cooler including: a pair of .Iadd.dry-air evaporatormodules and each comprised of .Iadd.two spaced members and .Iaddend.acore means having opposite interfaces .Iadd.separating the space betweensaid two spaced members into, and .Iaddend.establishing two air passageswith wetting means at one interface engaging a primary evaporativecolumn of air and with the other interface engaging a secondary sensiblecooled column of air with heat transfer between said oppositeinterfaces, both said separate columns of air being .[.moveable.]..Iadd.movable .Iaddend.by blower means through said two angularlyrelated passages, .Iadd.said core means comprising a multiplicity ofspaced, parallel, rigid and self-supporting tubes of plastic materialmounted at their ends in end headers mounted to said spaced membersperpendicular thereto, said end headers defining one of said angularlyrelated air passages through the tubes and through the opposite endheaders, said cooler module comprising means including said spaced,parallel, rigid and self-supporting tubes of plastic material forproducing substantially the same temperature decrease as a cooler modulethat is substantially the same in size, shape and operation as saiddry-air evaporator modules, but including metal tubes havingsubstantially the same length, rigidity, dimensions, spacing betweenthem, air flow through them and over them, and water flow over them, assaid dry-air evaporator module, .Iaddend.and a diffuser means dividingthe secondary sensible cooled column of air from one evaporator moduleand delivering separate primary and secondary columns of air through therespectively complementary passages therefor of the other evaporatormodule, thereby effecting a second stage of sensible cooling with cooleddry evaporative air.
 16. The compound dry-air evaporator cooler as setforth in claim 15 wherein separate blower means moves the separateprimary evaporative columns of air through each of the pair ofevaporator modules respectively.
 17. The compound dry-air evaporatorcooler as set forth in claim 15, wherein separate blower means moves thesecondary sensible cooled column of air through the pair of evaporatormodules.
 18. The compound of dry-air evaporator cooler as set forth inclaim 15, wherein separate blower means moves the secondary sensiblecooled column of air through the pair of evaporator modules, and whereinseparate blower means moves the separate primary evaporative columns ofair through each of the pair of evaporator modules respectively.
 19. Thecompound dry-air evaporator cooler as set forth in claim 15 wherein thediffuser means comprises a full flow intake from said one evaporatormodule and a restrictive outlet into at least one passage of said otherevaporator module.
 20. A dry-air evaporator pre-cooler for mechanicalrefrigeration means, and including; a core means having oppositeinterfaces establishing two air passages with wetting means at oneinterface engaging a primary evaporative column of air and with theother interface engaging a secondary sensible cooled column of air withheat transfer between said opposite interfaces, blower means moving theprimary evaporative column of air through said passage therefor, and themechanical refrigeration means having a condenser and an air blowermeans with an intake drawing the secondary sensible cooled column of airthrough said condenser from the pasage therefor, whereby said mechanicalrefrigeration condensor operates with sensible cooled air at asubstantially reduced intake temperature.
 21. The dry-air evaporativepre-cooler as set forth in claim 20 wherein the intake drawing of thesecondary sensible cooled column of air through the pre-cooler passagetherefor is directed through heat absorption means of said mechanicalrefrigeration means.
 22. The dry-air evaporative pre-cooler as set forthin claim 20 wherein the intake drawing of the secondary sensible cooledcolumn of air through the pre-cooler passage therefor is directedthrough sensible cooling means of said mechanical refrigeration means.23. The dry-air evaporative pre-cooler as set forth in claim 20 whereinthe intake drawing of the secondary sensible cooled column of airthrough the pre-cooler passage therefor is directed through both thesensible cooling means and said heat absorption means of said mechanicalrefrigeration means. .Iadd.24. The dry-air evaporative cooler as setforth in claim 1, wherein the wetting means is gauze wrapping at theexterior inrterfaces of said tubes..Iaddend. .Iadd.25. The dry-airevaporative cooler as set forth in claim 1 in which said tubes have onthe order of 1/16 inch all thickness. .Iaddend. .Iadd.26. The dry-airevaporative cooler of claim 1 in which said tubes extend betweenrectangular frame members which are entirely open to said primaryevaporative column of air on opposite sides of said tubes in a directionnormal to said tubes. .Iaddend. .Iadd.27. The dry-air evaporative coolerof claim 10 in which said tubes extend between rectangular frame memberswhich are entirely open to said primary evaporative column of air onopposite sides of said tubes in a direction normal to said tubes,whereby said modules are adapted to be placed side-by-side for formmulti-unit height. .Iaddend. .Iadd.28. The dry-air evaporative cooler ofclaim 20 in which each of said core means is comprised of a multiplicityof spaced parallel tubes extending between opposite end headers,coextensively between said pair of spaced side members, the exterior ofsaid tubes forming said one interface and the interior of said tubesforming said other interface. .Iaddend. .Iadd.29. The dry-airevaporative cooler of claim 28 in which said tubes are self-supportingplastic pipes. .Iaddend. .Iadd.30. The dry-air evaporative cooler as setforth in claim 1 further comprising means for passing said primaryevaporative column of air over said wetting means, and means for passingsaid secondary sensible cooled column of air through said tubes ofplastic material. .Iaddend. .Iadd.31. The dry-air evaporative cooler asset forth in claim 33 further comprising means for passing sensiblycooled air from said dry-air evaporative cooler over tubes of plasticmaterial in at least one additional dry-air evaporative cooler..Iaddend.